As a secondary battery is applied to more various fields and more developed devices, the capacity demanded required for the secondary battery is getting larger. Also, as the capacity is increasing, the importance of the technology for efficiently cooling the heat generated in the secondary battery is growing.
Referring to FIGS. 1 to 3, the structure of a conventional battery module assembly 1 and the structure of a battery module 2 applied thereto are shown.
First, the structure of the conventional battery module 2 is described with reference to FIG. 1. At least one paste injection hole 2a is formed on a bottom surface of the battery module 2 in order to coat a thermal paste onto an inside of the battery module 2, and at least one paste discharge hole 2b is also formed to check whether the injected paste fills the entire inner space or not.
The conventional battery module 2 configured as above is designed to stably fix a battery cell C and improve thermal conduction by injecting a thermal paste through an injection hole H1 to fill the space between the battery cell C in the battery module 2 and a module case with the thermal paste.
After the process of filling the thermal paste in the battery module 2 is completed, a cooling plate 3 is attached to a bottom surface of the battery module 2. In order to attach the cooling plate 3, a thermal paste is applied to the bottom surface of the battery module 2 again and then the cooling plate 3 is attached thereto.
However, if the thermal paste is applied to the bottom surface of the battery module 2 for the attachment of the cooling plate 3, it is not guaranteed that the thermal paste is uniformly applied between the battery module 2 and the cooling plate 3, and it is also not guaranteed that the thermal paste spreads uniformly when the cooling plate 3 is coupled. Thus, a thermal resistance may increase at the interface between the bottom surface of the battery module 2 and the cooling plate 3.
In addition, if the process of coating a thermal paste to the inside of the battery module 2 and the process of coating a thermal paste to the bottom surface of the battery module 2 for the attachment of the cooling plate 3 are performed separately as described above, the coating process should be performed repeatedly, which is also disadvantageous in terms of productivity.